Lithium tantalate (LiTaO3) single crystals having different Li/Ta ratios were grown by using conventional and double crucible Czochralski method. The grown crystals appeared to have mole percent of Li2O ranging from 45.5 to 50 mol%. We analyzed the real composition with ICP method and measured the Curie temperatures (T-c) with DTA method. The relationship between T-c and the mole percent of Li2O in LiTaO3 crystals was derived. The transmission spectra and refractive indices were measured. The refractive indices measured by prism coupler were analyzed in terms of single-term Sellmeir parameters.